Steering axle drive assembly and method for controlling said drive assembly

ABSTRACT

A steering axle drive assembly includes a steering axle having opposite ends, a wheel pivotally connected with each steering axle end, and a control mechanism. The wheels are operated by the control mechanism for rotation about a vertical axis and a horizontal axis. When the axle is connected with a vehicle, the control mechanism controls the steering axle wheels independent of other wheels of the vehicle, such as the main drive wheels, to steer and drive the vehicle from an origin in any direction without passing through the origin. Preferably, a motor or linear actuator controls the rotation of the steering axle wheels. The steering axle drive assembly can be further improved by including an angled axle.

This application is based on U.S. provisional application Nos.62/808,959 filed on Feb. 22, 2019 and 62/832,457 filed on Apr. 22, 2019,the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

The present disclosure relates generally to an axle for a vehicle, andmore specifically to an axle for a zero radius turn mower or tractor.

Zero radius turn vehicles are often found in commercial mowingoperations and are typically controlled by twin levers which directly orthrough linkages move trunnions on variable displacement hydraulicpumps. The variable displacement pumps are connected to motors that areconnected to two drive wheels. The twin levers control the left andright drive wheel speeds and forward and reverse directions,respectively. Caster wheels, which provide neither traction nordirectional stability, are suspended at the end of the vehicle oppositethe end with the drive wheels. Moving one lever forward and the otherlever in reverse can produce a zero radius turn, though doing so ofteninvolves dragging of the caster wheels. Sometimes, in order totransition from a zero radius turn to the left to a sharp turn to theright, the mower might need to complete a multipoint turn, moving inboth forward and reverse directions to reach a desired location.

With more recent mowers, a steering wheel is provided which controls aset of wheels that replace the caster wheels. These wheels aremechanically steered by a traditional steering wheel and can be used toachieve a zero radius turn. These mowers offer side slope performancebenefits, whereas mowers with non-controlled caster wheels do not.

In addition to existing zero radius turn mowers with steering wheels,the Haun U.S. Pat. No. 9,538,706 discloses controlling such wheels whichcan rotate about their vertical axes based on signals generated by theposition of the twin steering levers. Such a design has drawbacks.Though a vehicle as disclosed by Haun could complete a zero radius turnand other important maneuvers, the wheels would have to rotate abouttheir vertical axes back to a straight-ahead position before changingthe direction of the vehicle. Typically one is not required tostraighten the steering wheels when backing up after making a forwardleft or right turn. Parallel parking would be quite tedious, especiallyfor a vehicle with purportedly enhanced maneuverability.

As to tractors, they typically have large rear wheels which are notsteered, and a front axle with smaller wheels which are steered. Sometractor-based vehicles like lift trucks, back-end loaders,self-propelled windrowers, and certain mowers include steered wheels atthe rear of the vehicle. These vehicles have the same platform astractor-based vehicles with front-steered wheels but are driven inreverse. Independent left and right brakes on the main drive wheels,which are typically the large rear wheels, allow for sharper turns byslowing the inside wheel and shifting torque to the outside main drivewheel, resulting in a decreased turning radius. Because of mechanicallimits of traditional steer axles, this decreased turning radius bybraking the inside wheel results in scuffing. In theory, a traditionaltractor can make a turn while in four-wheel drive by turning about themain drive wheel that is locked in place by its brake, but in practice,the geometry of the front axle prevents such a tight turn.

For tractors known in the art, when the inside wheel is locked, thesteering angles of the front wheels do not allow the axes of the frontwheels to intersect at the rear inside wheel. To do so, the front rightwheel would have to be perpendicular to the length of the tractor. Knownsteered wheels, especially driven ones, do not turn that sharply. Theresult of locking the right rear wheel on a traditional tractor, evenwhen the front wheels are steered all the way to the right or left, isthat the front wheels are dragged, the left or right rear wheel slips,and the right or left rear wheel slides. Independent brakes help atractor turn more sharply, but the tractor prevents a pivot turn.

There is thus a need for mowers, tractors or similar vehicles tofunction such that a zero-radius turn can be completed more efficiently,and sharp turns or other challenging maneuvers can be completed withsimpler controls.

SUMMARY OF THE DISCLOSURE

Accordingly, it is an object of the present disclosure to provide asteering axle drive assembly which independently controls the wheelsopposite the main drive wheels of a vehicle. The steering axle driveassembly includes a steering axle having opposite ends, a wheelpivotally connected with each steering axle end, and a controlmechanism. The wheels are operated by the control mechanism for rotationabout a vertical axis and a horizontal axis. When the axle is connectedwith a vehicle, the control mechanism controls the steering axle wheelsindependent of other wheels of the vehicle, such as the main drivewheels, to steer and drive the vehicle from an origin in any directionwithout subsequently passing through the origin. Preferably, a motor orlinear actuator controls the rotation of the steering axle wheels.

In a preferred embodiment, the control mechanism includes a joystickconnected with a controller. The controller receives a coordinate inputfrom the joystick and provides an output to the steered axle to controlthe rotation of the wheels about the respective vertical and horizontalaxes. In this embodiment, the controller sends signals to an actuator tocontrol the wheels about both the vertical and horizontal axes.

In an alternate embodiment, a first signal is sent to a firstcontroller, via a joystick or other control mechanism, for rotating thewheels about their horizontal axes, and a second signal is sent to asecond controller, for rotating the wheels about their vertical axes.The first and second signals are associated with control mechanism x andy input values, respectively.

In yet another embodiment, the control mechanism includes a steeringwheel for steering the wheels and a lever for driving the wheels forwardor reverse, independent of another axle and other wheels on the vehicle.

In embodiments which include a controller, there is preferably at leastone operator interface such as a switch, button, lever or pedal forcontrolling the steering axle wheels about their vertical and horizontalaxes via a motor, linear actuator, or brake.

In a further embodiment, an independently controlled brake is connectedwith each of the steering axle wheels to restrict rotation of the wheelsabout the respective vertical axes. A steering angle is defined when atleast one of the brakes is independently applied to a wheel and thewheels are independently driven about their respective horizontal axes.

It is also an object of the present disclosure to provide an axleassembly for a vehicle that includes a symmetrically angled axle andwheels pivotally connected with the axle. The axle has a midsection andaxle ends and is connectable with the vehicle such that the midsectionis arranged forward of the axle ends. The wheels are connected with theaxle ends for rotation about a vertical axis and a horizontal axis. Whenthe symmetrically angled axle is connected with the vehicle, the wheelsare pivotable about their respective vertical axes to a position inwhich radii extend from a center point of a second axle through eachhorizontal axis to define a geometric relationship between the angledaxle wheels and the second axle. This geometric relationship allows thevehicle to complete a zero radius turn without sliding or scuffing.

In a preferred embodiment, the axle assembly further includes a hingeassembly connected with each of the axle ends and wheels. The hingeassemblies have a pivot pin that is coaxial with an associated verticalaxis.

It is further an object of the present disclosure to provide a methodfor completing a zero radius turn for a vehicle. The vehicle includesthe above described steering axle drive assembly as well as anadditional wheeled axle, a transmission, a left wheel and brake, and aright wheel and brake. The left and right brakes of the additionalwheeled axle are independently controlled. The method includes the stepsof rotating the steering axle drive assembly wheels about the verticalaxis in a left or right direction, braking a left wheel of the secondwheeled axle in response to rotating the wheels of the first wheeledaxle in a right direction and braking the right wheel of the secondwheeled axle in response to rotating the wheels of the first wheeledaxle in a left direction, driving the wheels of the first wheeled axleabout the respective horizontal axes in a forward direction, and drivingthe unbraked wheel of the second wheeled axle about its horizontal axisin a reverse direction.

BRIEF DESCRIPTION OF THE FIGURES

Other objects and advantages of the disclosure will become apparent froma study of the following specification when viewed in the light of theaccompanying drawing, in which:

FIG. 1 is a perspective view of a first embodiment of a zero radius turnmower having a steering axle drive assembly according to the presentdisclosure;

FIG. 2 is a schematic view of a first embodiment of a tractor having asteering axle drive assembly according to the present disclosure;

FIG. 3 is a schematic view of a second embodiment of a tractor having asteering axle drive assembly according to the present disclosure;

FIG. 4 is a schematic view of a third embodiment of a tractor having asteering axle drive assembly according to the present disclosure;

FIG. 5 is a schematic view of a fourth embodiment of a tractor having asteering axle drive assembly according to the present disclosure;

FIG. 6 is a schematic view of an embodiment of a zero radius turn mowerhaving a steering axle drive assembly according to the presentdisclosure;

FIG. 7 is a schematic view of another embodiment of a zero radius turnmower having a steering axle drive assembly according to the presentdisclosure; and

FIG. 8 is a flow chart showing a method for completing a zero radiusturn of a vehicle according to the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to a steering axle drive assembly for avehicle and a method for completing a zero radius turn with a vehiclethat has the drive assembly. Referring to FIG. 1, there is shown a firstembodiment of the assembly used with a zero radius turn mower 2. Themower has a steering axle drive assembly 4 and rear axle assembly 6,each of which include a pair of wheels 8 a, 8 b and 10 a, 10 b connectedwith each associated axle 12, 14. The front axle wheels 8 a, 8 b a arepivotally connected with each steering axle end for rotation about avertical axis V and rotation about a horizontal axis H, respectively,independent of any controls related to the rear axle wheels 10 a, 10 b.A control mechanism 16 controls the position of each front steering axlewheel 8 a, 8 b about each respective vertical and horizontal axis. Thecontrol mechanism 16 includes a joystick 18, a controller 20 and motors22 a, 22 b. When the right joystick 18 is pivoted forward or back, ay-axis signal is sent to the controller 20 which engages the motors 22a, 22 b to rotate the wheels 8 a, 8 b forward or reverse, respectively.When the joystick 18 is pivoted left or right, an x-axis signal is sentto the controller which engages the motors to rotate the wheels 8 a, 8 bleft or right, respectively. The controller can process both x and ysignals simultaneously. Levers 24 a, 24 b connected with the rear axle14 are pushed forward or pulled back to control the rear wheels 10 a, 10b, respectively. The front wheels 8 a, 8 b are thus steered and drivenaccording to the inputs from the joystick 18 to the controller 20independent of any control over the rear wheels 10 a, 10 b. It will beunderstood by those with skill in the art that, as detailed below, thecontrol mechanism 16 could involve one or more joysticks, or other suchdevices, one or more controllers, one or more motors, or another methodfor rotating the steered axle wheels. Preferably, the steered axlewheels 8 a, 8 b rotate about a vertical axis V over a range of at least150-degrees and more desirably a range from 180- to 360-degrees.

Referring now to FIGS. 2-5, embodiments of the steering axle assemblyconnected with tractors are shown. FIG. 2 shows a first tractor 102 witha steering axle drive assembly 104 attached thereto. The steering axledrive assembly 104 includes front wheels 108 a, 108 b that are connectedto ends of an angled steering axle 112 and controlled via linearactuators 122 a, 122 b, for instance pneumatic or hydraulic cylinders,which selectively prevent the wheels from rotating about pins 126 a, 126b when a steering set point is reached, and by selectively allowing thewheels to rotate around the ends of the axle 112 when a steering anglechange is initiated. The control mechanism 116 is connected with acontroller 120 to drive the wheels forward and reverse via a joystick118 a. Buttons 118 b, 118 c engage the right and left actuator,respectively, to steer the wheels. The steering axle drive assembly 104of this embodiment also includes a pair of brakes 128 a, 128 bcontrolled via brake pedals 130 a, 130 b for restricting horizontalrotation of each steering axle wheel 108 a, 108 b. The rear wheels 110a, 110 b are controlled via a treadle 132 which is connected with atransmission 134 and differential 136. The treadle drives the rearwheels 110 a, 110 b forward and reverse, and rear wheel brakes 138 a,138 b restrict horizontal rotation of each rear wheel 110 a, 110 b,respectively. They are controlled via rear brake pedals 140 a, 140 b.

Referring to FIG. 3, there is shown a tractor 202 that includes asteering axle drive assembly 204 with wheels 208 a, 208 b and a rearaxle assembly 206 with wheels 210 a, 210 b. The front wheels 208 a, 208b are connected with the end of an angled steering axle 212 and arecontrolled via a control mechanism 216, brakes 228 a, 228 b, 228 c, 228and motors 222 a, 222 b. The control mechanism includes a first set ofbuttons 218 a, 218 b for controlling drive brakes 228 a, 228 b,respectively, and a second set of buttons, 218 c, 218 d for controllingsteering brakes 228 c, 228 d, respectively. There is also a centrallylocated switch 218 e for shifting a front transmission 242 into forwardor reverse and for driving the motors 222 a, 222 b. The fronttransmission is further connected with a front differential 244 forcontrolling the torque of the front wheels 208 a, 208 b. As with thetractor in FIG. 2, there are rear wheels 210 a, 210 b controlled via atreadle 232, a transmission 234, a differential 236 and rear wheelbrakes 238 a, 238 b, which are controlled by pedals 240 a, 240 b,respectively.

FIG. 4 shows a tractor 302 that includes a steering axle drive assembly304 and rear axle assembly 306, similar to those shown in FIGS. 2 and 3.The steering axle drive assembly includes wheels 308 a, 308 b connectedwith an angled steering axle 312, and the rear axle assembly includeswheels 310 a, 310 b connected with a rear axle 314. The rear axle wheelsare driven forward or reverse via a treadle 332, a transmission 334, anda differential 336. Rear brakes 338 a, 338 b are controlled via pedals340 a, 340 b. Similar to FIG. 2, the steering axle drive assemblyincludes drive brakes 328 a, 328 b for restricting horizontal rotationof the front wheels 308 a, 308 b, respectively, which are engaged bypedals 330 a, 330 b. The front wheels 308 a, 308 b are driven forwardand reverse and steered left and right via a control mechanism 316 whichincludes a joystick 318, a controller 320, a transmission 342, andmotors 222 a, 222 b connected with their respective wheels.

The embodiment shown in FIG. 5 is similar to those of FIGS. 2-4 but thecontrol mechanism 416 includes a steering wheel 418 a and a drive lever418 b connected with a transmission 442 and a differential 444. Thefront wheels 408 a, 408 b are driven and steered independent of the rearwheels 410 a, 410 b, and are electrically controlled. As with the othertractor embodiments, there is a steering axle drive assembly 404 and arear axle drive assembly 406, each of which includes an axle 412, 414.There are also rear brakes 438 a, 438 b and brake pedals 440 a, 440 b,respectively. The steering wheel 418 a is connected with the frontwheels 308 a, 308 b to rotate them about their vertical axes, and thedrive lever 418 b is connected with the transmission 442 to drive thewheels forward or reverse. A treadle 432 is connected with a rear axletransmission 434 and differential 436 to drive the rear wheels forwardand reverse.

Referring now to FIGS. 6 and 7, embodiments of a zero radius turn mowerwith a steering axle assembly are shown. In FIG. 6, the mower 502 has asteering axle drive assembly 504 with wheels 508 a, 508 b that arecontrolled independent of the vehicle rear wheels 510 a, 510 b. Thevehicle includes a front 512 axle with front wheels 508 a, 508 b and acontrol mechanism 516 for controlling rotation of the front wheels abouttheir vertical V and horizontal H axes. The mower 502 also includeslevers 524 a, 524 b connected with the rear wheels 510 a, 510 b forcontrolling the driving force of those wheels. There is an engine anddual hydrostatic pump drive or dual electric motor 536 for controllingthe torque of the rear wheels. The control mechanism 516 of thisembodiment includes buttons 518 a, 518 b, 518 c, 518 d arranged on thelevers 524 a, 524 b and drive pedals 530 a, 530 b. The levers are pushedforward or pulled back to drive the tractor forward or reverse,respectively. The buttons are engaged to send a signal to a controller520 which in turn causes motors 522 a, 522 b to steer the wheels 508 a,508 b. The pedals 530 a, 530 b are pushed to engage additional motors522 c, 522 d to drive the wheels.

FIG. 7 shows a zero radius turn mower 602 with a steering axle driveassembly 604 which is similar to the mower shown in FIG. 6, but thecontrol mechanism 616 for controlling the front wheels 608 a, 608 bincludes a single joystick 618 arranged on the right drive lever 624 b.The joystick 618 is moved forward/back and left/right to provide x and ysignals, respectively, to a controller 620, which in turn engages motors622 a, 622 b to steer and drive the wheels according to the signalsreceived by the controller. As with the mower of FIG. 6, the mowerincludes an engine and dual hydrostatic pump drive or dual electricmotor 636 and rear wheels 610 a, 610 b which are controlled via drivelevers 624 a, 624 b. The front pedals 630 a, 630 b apply brakes forcontrolling the horizontal rotation of the front wheels 608 a, 608 b.

Referring now to FIG. 8, there is shown the method steps for controllinga vehicle to complete a zero radius turn. This allows the vehicle todrive directly to a location without the need for a multipoint turninvolving both forward and reverse directions. The steps includeindependently rotating the wheels of the front axle about theirrespective vertical axes in a first direction to the left or right, andindependently rotating at least one wheel of the rear axle about ahorizontal axis forward or reverse.

More specifically, a method for controlling the tractor 302 of FIG. 4will now be described. To turn to the right, the steering axle wheels308 a, 308 b of the first wheeled axle 310 are rotated about theirvertical axes V to the right, a brake 334 a is applied to the rear leftwheel 310 a of the second wheeled axle 314, the front wheels are drivenabout their horizontal axes H in a forward direction, and the rightwheel 310 b of the second wheeled axle is driven in reverse. To completea turn to the left, the opposite is done. That is, the front wheels 308a, 308 b are steered to the left, a brake 334 b is applied to the rearright wheel 310 b, the front wheels are driven forward, and the rearleft wheel 310 a is driven in reverse. This allows for a zero radiusturn without any scuffing or dragging of the front wheels.

Referring again to FIG. 6, additional methods for maneuvering a vehiclehaving the steering axle drive assembly disclosed herein are described.The mower 502 includes four normally open momentary button switches 518a, 518 b, 518 c, 518 d. When the left switches 518 a, 518 b aredepressed, a steering motor 522 a rotates the front left wheel 508 aabout the left pin 526 a to the left about its vertical axis V. The leftpedal 530 a is engaged to send a signal to the controller 520 to powerthe hub motor 522 c to drive the left wheel 508 a in reverse.Alternatively, to steer the front left wheel 508 a to the right, onlythe left most button 518 a is depressed. The control of the left pedaland hub motor can be switched to drive the left wheel 508 a forward.

The right switches 518 c, 518 d and right pedal 530 b perform similarfunctions on the front right wheel 508 b. When both switches 518 c, 518d are depressed, the steering motor 522 b rotates the right wheel 508 babout the right pin 526 b to the left about its vertical axis V. Tosteer the front right wheel to the right, only one button 518 c isdepressed. The right pedal 530 b is engaged to signal the controller 520to power the hub motor 522 d to drive the right wheel 508 b in reverse.The control of the pedal and hub motor can be switched to drive thewheel forward.

It will be obvious to those skilled in the art that many differentsystems and switches might be used to control the steering motors andwheel speeds. Also, depending on terrain and size of the steering motor,the wheels may need to apply a braking force when the vehicle is movingrather than actually rotating the inside wheel backward. For instance,to turn left while the vehicle is going forward, a brake must be appliedto the left front wheel, while the left steering motor turns the wheelto the left.

Referring again to FIG. 6, to make a left turn, both left switches 518a, 518 b on the left lever 524 a are pressed to signal the steeringmotor 522 a to steer the left wheel 508 a to the left, and both switches518 c, 518 d on right lever 524 b are pressed to signal the steeringmotor 522 b to steer the right wheel 508 b to the left. The right lever524 b is then pushed further forward than the left lever 524 a to drivethe right rear wheel 510 b faster than the left rear wheel 510 a. Tomake a right turn, one button 518 a on the left lever 524 a is pressed,one button 518 d on the right lever 524 b is pressed, and the left lever524 a is moved further forward than the right lever 524 b. It will beunderstood by those with skill in the art that, rather than usingbuttons to complete these turns, a steering wheel with pedals or a lever(as shown in FIG. 5) can be used. Further, as shown in FIG. 7, ajoystick and controller can be used to produce the signals that causethe motors to steer and drive the wheels.

In the embodiment of FIG. 6, there are pins 526 a, 526 b havingsensors/indicators for aiding the operator of the vehicle withcoordinating angles of the wheels 508 a, 508 b, preferably withdemarcations so that individual turning radii can be chosen. This allowsthe operator to know when the two steering angles correspond to Ackermansteering, and whether the horizontal axes H of both wheels 508 a, 508 bpoint to a specific location on the rear axle 514.

In this embodiment, a controller 520 receives steering command inputfrom an operator through an operator interface 546 which receivessignals from the buttons 518 a, 518 b, 518 c, 518 d. Sensors 526 a, 526b send signals to the controller 520 which can calculate Ackerman orother desired geometries when performing the steering command inputreceived from the control mechanism 516. As is shown in the otherembodiments described above, a joystick or joysticks, steering wheel,pedals, levers or other devices can be substituted for the buttons 518a, 518 b, 518 c, 518 d. Further, an algorithm, or indicator referencemarks, can be substituted for the operator's judgement.

For this embodiment, the operator manually controls the speeds of therear drive wheels 510 a, 510 b. It is easier to steer first and thencoordinate the wheel speeds than it is to do both simultaneously. Thepin with sensors 526 a, 526 b measure the steering angles and thecontroller 520 uses that information to dictate the actions of thesteering motors in accordance with the steering command from the controlmechanism 516.

Referring again to FIGS. 2-5, there is shown an angled steering axle112, 212, 312, 412. The axle is angled such that a midsection 148, 248,348, 448 is arranged forward of axle ends 150, 250, 350, 450. When thewheels of these angled axles are rotated about their vertical axis toperform a turn, they can be steered to a position in which two radiiextend from a center point of the rear axle 114, 214, 314, 414, throughthe horizontal axis of each front wheel to define a preferred geometricrelationship between the angled axle wheels and the rear axle, such aswith Ackerman steering. The tractor can then complete a zero-radius turnwithout sliding or scuffing. It will be understood by those of skill inthe art that such an angled axle can be incorporated with the mowers ofFIGS. 1, 6 and 7, as well as with other similar vehicles.

Preferably, the above-noted angled axles are configured to form a135-degree angle, but it will be understood by those with skill in theart that other angles that achieve the same geometric goals as describedherein could be used.

Regardless of the vehicle with which the angled axle is used, the frontsteering wheels of that axle each have a horizontal and vertical axisabout which each wheel rotates. Referring again to FIG. 3, anothermethod for steering and driving a tractor will be described. First, boththe vertical axes brakes 228 c, 228 d are released, one of thehorizontal axis brakes 228 a, 228 b of one wheel is engaged, and thehorizontal axis brake of the other wheel is released. The front wheels208 a, 208 b are then driven. The wheel without the horizontal axisbrake engaged will be driven forward, while the wheel with thehorizontal axis brake engaged will rotate about its vertical axiscausing the mower to turn. The brakes and driving force of the two frontwheels can be varied to steer the front wheels.

The vertical axis brake may be a traditional friction brake but mightalso be a hydraulic cylinder and rod. The steered wheels of the angledaxle may rotate many degrees about their vertical axes, approaching 180degrees or more. Hydraulic cylinders and rods cannot generate rotarymotion of 180 degrees by themselves but can act as a brake over morethan 180 degrees. When the brake is released, the wheel can move freelyaround the vertical axis to steer the machine, which is achieved byapplying a driving force to the wheel. When the brake is applied, anydriving force of the associated wheel drives the machine rather thansteers it. It will be understood by those with skill in the art, thatthe wheels can be steered via a motor rather than with releasing one ormore vertical axes brakes.

In addition to improved turning from the angled axle, an independenttransmission on the front wheels further improves the effectiveness of azero radius turn or any forward turn which is sufficiently sharp suchthat a rear wheel moves backwards. For instance, for a right turn wherethe tractor pivots about the right rear wheel, the axle allows thehorizontal axes of the two front wheels to intersect at the right rearwheel. When the left rear wheel and the front wheels are driven forward,the right rear wheel is stationary, and a turn is achieved that issharper and more effective than with other tractor axles known in theart.

In addition to mechanical or electric controls, the angled steering axlecan be controlled by an electronic operator interface and/or a joystick.The x and y axes of the joystick provide directions to front wheels of atractor that is retrofitted with the angled axle described above. Theoperator provides instructions to the front axle and the wheels mountedon it to drive forward and reverse and to steer with an Ackermangeometry as calculated by a controller. The operator is then tasked withthe mechanical duties of operating the foot clutch, the manualtransmission shift lever and rear wheel brakes.

Although the above description references particular embodiments, it isto be understood that these embodiments are merely illustrative of theprinciples and applications of the present disclosure. It is thereforeto be understood that numerous modifications may be made to theillustrative embodiments and that other arrangements may be devised andemployed without departing from the spirit and scope of the presentdisclosure.

What is claimed is:
 1. A steering axle drive assembly for a vehicle,comprising: a. a steering axle having opposite ends; b. a wheelpivotally connected with each steering axle end for rotation about avertical axis and rotation about a horizontal axis; and c. a controlmechanism controlling the position of each of said steering axle wheelsabout each respective vertical axis and driving said steering axlewheels about each respective horizontal axis, said control mechanismcontrolling said steering axle wheels independent of other wheels of thevehicle to steer and drive the vehicle from a first angle and pathdirectly to any other angle and path without passing through the originof the first angle and path.
 2. A steering axle drive assembly asdefined in claim 1, wherein each of said steering axle wheels isrotatable through an angle of at least 150-degrees about the respectivevertical axis.
 3. A steering axle drive assembly as defined in claim 1,wherein each of said steering axle wheels is rotatable between180-degrees and 360-degrees about the respective vertical axis.
 4. Asteering axle drive assembly as defined in claim 1, wherein said controlmechanism includes a joystick connected with a controller, saidcontroller receiving a coordinate input from said joystick and providingan output to said steering axle wheels to control the rotation of saidsteering axle wheels about the respective vertical and horizontal axes.5. A steering axle drive assembly as defined in claim 1, wherein saidcontrol mechanism includes a steering wheel and at least one lever tocontrol the rotation of said steering axle wheels about the respectivevertical and horizontal axes.
 6. A steering axle drive assembly asdefined in claim 1, wherein said control mechanism provides a firstsignal to said wheels for rotation about said horizontal axis andprovides a second signal to said wheels for rotation about said verticalaxis, said first signal and said second signal being associated withcontrol mechanism x and y input values, respectively.
 7. A steering axledrive assembly as defined in claim 1, and further comprising at leastone operator interface including at least one of a switch, button, leverand pedal for controlling said steering axle wheels about one of theirvertical and horizontal axes via one of a motor, linear actuator, orbrake.
 8. A steering axle drive assembly as defined in claim 1, whereinone of at least one motor and at least one linear actuator controls therotation of said steering axle wheels about said vertical axes,respectively.
 9. A steering axle drive assembly as defined in claim 8,wherein said linear actuator comprises one of a hydraulic cylinder,pneumatic cylinder and electric actuator.
 10. A steering axle driveassembly as defined in claim 1, and further comprising an independentlycontrolled brake connected with each of said steering axle wheels.
 11. Asteering axle drive assembly as defined in claim 10, wherein each ofsaid independently controlled brakes restricts rotation of each of saidsteering axle wheels about the respective vertical axis, whereby asteering angle is defined when at least one of said brakes isindependently applied to a steering axle wheel and said steering axlewheels are independently driven about their respective horizontal axes.12. A steering axle drive assembly as defined in claim 1, wherein saidsteering axle has a symmetrically angled configuration connectable withthe vehicle such that a steering axle midsection is arranged forward ofsaid steering opposite ends.
 13. An axle assembly for a vehicle,comprising: a. a symmetrically angled axle having a midsection and axleends connectable with the vehicle such that said midsection is arrangedforward of said axle ends; and b. a wheel pivotally connected with eachaxle end for rotation about a vertical axis and rotation about ahorizontal axis, whereby when said symmetrically angled axle isconnected with the vehicle, each of said wheels is pivotable about eachrespective vertical axis to a position in which radii extend from acenter point of a second axle through each horizontal axis to define ageometric relationship between said angled axle wheels and the secondaxle, whereby the vehicle can complete a zero radius turn withoutsliding or scuffing.
 14. An axle assembly for a vehicle as defined inclaim 13, and further comprising a hinge assembly connected with each ofsaid axle ends and each of said wheels, each hinge assembly having apivot pin coaxial with an associated vertical axis.
 15. A steering axledrive assembly as defined in claim 13, wherein said symmetrically angledaxle comprises one of a generally V and U shape.
 16. A steering axledrive assembly as defined in claim 15, wherein said ends of saidsymmetrically angled axle are arranged at an angle between 130-140degrees relative to a plane tangent to said axle midsection.
 17. Amethod for completing a zero radius turn for a wheeled vehiclecomprising the steps of: a. independently rotating the wheels of a firstwheeled axle about vertical and horizontal axes, respectively; and b.independently rotating at least one wheel of a second wheeled axle abouta horizontal axis.
 18. A method for completing a zero radius turn asdefined in claim 17, and further comprising the steps of: a. rotatingthe wheels of the first wheeled axle about the vertical axis in one of aleft and right direction; b. braking a left wheel of the second wheeledaxle in response to rotating the wheels of the first wheeled axle in aright direction and braking the right wheel of the second wheeled axlein response to rotating the wheels of the first wheeled axle in a leftdirection; c. driving the wheels of the first wheeled axle about therespective horizontal axes in a forward direction; and d. driving theunbraked wheel of the second wheeled axle about its horizontal axis inin a reverse direction.